Expansion valve for refrigerating systems



1931- A. F. S AWYER' EXPANSION VALVE FOR REFRIGERATING SYSTEMS FiledSept. 22. 192B Patented Feb. 17, 1931 UNITED STATES.

PATENT OFFICE ALBERT F. SAWYER, OF HAVERI- IILL, MASSACHUSETTS, ASSIGNORTO IRVING L. .KEITH, F I-IAVERHILL, MASSACHUSETTS EXPANSION VALVEFORREFRIGERATING SYSTEMS Application fi1ed Septemher 22, 1928. Serial No.307,630.

This invention relates to expansion valves of the type of which areemployed in closed circuit expander, compressor, condenser refrigeratingsystems, to control the supply of refrigerant to the expansion coil orchamher, and more ymrticularly, .to a'pressure controlled type of valvewhich opens when the pressure, in the expansion chamber, .or the backpressure is reduced to a predetermined point and closes again when theback pressure-is raised to another predetermined point.

In devices of this type it is customary to V operate theneedle valve,which directly controls the passage through which thewrefrigerant passesto the expansion chamber,by vmeans of a diaphragm which is open to thelow pressure of the system at its inner side and is subject toatmospheric pressure at its outer side, this action, usually beingsupple- ZOinentedby a spring, the action of which is usually partlyneutralized by a spring of lighter weight located within the casmg, and

the arrangement being such that when the pressure in the expansionchamber is reduced to such an extent that the combined action of thispressure and of the light weight spring is over balanced by theatmospheric pressure and the action of the heavier spring, the needlevalve will be opened to permit. the .dischargeof refrigerant from thehlgh pressure side to the low pressure side of the system.

.In practice the means for causing the needle valve to be openedsometimes fail to act, so that a dangerously high pressure 1s likelytobe built up in such case. .Thls failvure ofthe needle valve to open isfrequently due to an accumulation of frost, or ice on the diaphragm, sothat it becomesinflexible, or on coils of the outer spring for actuatingthe diaphragm, so that it is prevented fromacting to force the latterinward, and this 1s likely to occur eventhough the diaphragm andspringare encased to preventaccess of air thereto, the movement of thediaphragm tending to cause air to be drawn 1n to and out of the chamberin which it is encased.

The object of my invention is to provide a simpleand compact form ofvalve device of the type above referred to, in which the arforengagement with the inner side of the rangement is such that, when thesupply side of the systemis raised to a predetermined polnt above thenormal high pressure,but is still well below a pressure which would besystem and a port 3, adapted to be connected to the high pressure sidethereof. A needle jvalve 4: is provided in the casing and arranged toseat in the port 3 against the pressure of the high pressure side. Thestem 5 of said valve is provided with a central 10ngitudinal bore orchamber 6, which extends from the opposite end thereof for approx- ?5imately half its length, and a circular flange 7 is formed integrallywith said stem and has an annular rib 8 on its inner side. A flexiblediaphragm 9 is clampedto the open end of the casing by means of a cap 10and screws 11. A coiled spring 12 is arranged within the cap 10 inengagement at its inner end with the outer side of the diaphragm and anadjusting screw13 is threaded in the cap and in engagement with theouter end of said spring. -An actuating stem 14 is disposed inaXial'alignm-ent with the valve'stem 5 and is telescopically arranged inthe chamher 6 thereof, with its outer end in position diaphragm 9. Aspring 15 is interposed'between the inner end of the stem 14 and thebottom of chamber 6. A pair of levers 17 are extended in oppositerelation thru apertures 18 in the side of the chamber 6 of the valvestem and the inner ends thereof are disposed 1n an annular groove formedin stem 14, the outer ends thereof being arranged to engage the rib 8 0nflange 7, and

the middle portions thereof being fulcrumed on an annular rib 19 on thecasing l.

lVith the above described construction, when the pressure against theinner side of the diaphragm 9 is sutlicient to overcome the combinedaction of atmospheric pressure and of spring 12 on its outer side, thespring 15 will act to hold the valve 4 closed, as shown. in Fig. 1. Thisposition of the parts may be considered as the normal position. When thepressure within the casing is reduced to a iiredetermined point, so thatthe inward pressure over balances the ouward pressure on the diaphragm,it will be sprung inward, forcing the stem 14 inward and causing lovers1? to be swung so as to be forced against the flange 7 and open thevalve d against the action of spring 15, this action ted by the fluidpressure which is being built up against the valve in the high pressuresine of the system, or in port 3. This condition will continue until thecirculating ounip stops and, the pressure in the valve casing risessulliciently to ovcrl'ialance the inward pressure on the diaphragm and irmit the spring 15 to close the valve.

iassuming however, that the outer spring ihould become ineffective forany reason, as by having its coils become frozen together, or by havingthe diaphragm so stiffened by ice as to become inflexible, it will beapparent that when the pressure within the casing is reduced, thediaphragm will not be forced inward and in consequence, the valve 4 willnot be lifted from its seat thereby. The tens on of spring 15 is howeversuch that when the pressure in port 3 rises to a substantial extentabove that atwhich the valve would normally be opened by the inwardforce on the diaphragm, this pressure, acting against he valve l, willovercome the action of pring 15 and cause valve l to be unseated, .0that the refrigerant will pass from the ii gh pressure to the lowpressure side of the system, the pressure in the high pressure side thusbeing prevented from rising above a predetermined point. The danger ofhaving excessive or unsafe pressures built up in system from failure ofthe diaphragm to be moved inward is thus avoided. The construction alsois advantageous over a construction in which the pressure in the highressure side tends to hold the valve against its seat, which arrangementhas been commonly employed, as the higher the point to which thepressure rises the more diffcult it becomes to unseat the valve. On thecontrary with the above described construction, the higher the point towhich this pressure rises the more easily the valve is opened, so thatin case the valve should tend to stick or become frozen to its seat, thepressure against he valve will ordinarily act to open it, when itotherwise would not be opened automatically. In warm weather there isalso conside able tendency for the pressure in the high pressure side ofthe system to run substantially higher than in cool Wcaher, and thisincreased pressure tends to cause the valve 1 to be opened earlier andclose later with the above described construction, than would be thecase if the pressure tended to hold the valve to its seat, and thustended to restrict circulation when maximum circulation was desirable.

The above described construction is very compact, and may be housed inan ordinary cylindrical casing of practically the same form as theconstruction which has usually been employed for this purpose.

t is also simple and but slightly more expensive to manufacture thansuch prior construction.

I claim:

1. An expansion valve comprising a casing having an inlet port and anoutlet port respectively adapted for connection to the high pressureside and to the low pressure side of a closed circuit refrigerationsystem, a valve stem reciprocally movable within the casing and having avalve at one end, to be n'ioved against the pressure supplied to saidinlet port to close the same, a spring adapted and arranged to engagesaid stem and hold said valve closed against the normal fluid pressuresupplied to said inlet port and to yield to permit the valve to beopened by an abnormal pressure supplied thereto, a pressure controlleddevice on said casing arranged to be moved outwardly to an inoperativeposition by the pressure within the casing when raised to apredetermined point and to be moved inwardly from said position whensaid pressure is reduced below said point, and engaging means betweensaid device and said stem arranged to move said stem to open said inletport when said device is moved inwardly.

2. An expansion valve comprising a casing" having an inlet port and anoutlet port respectively adapted for connection to the high pressureside and to the low pressure side of a closed circuit refrigeration sstem, a valve having a. stem disposed within the casing andlongitudinally movable in one direction to close said inlet port againstthe pressure of the fluid supplied thereto and oppositely movable bysaid pressure to an open position, a spring arranged to engage said stemand to hold said valve in closed position against a normal pressuresupplied to said inlet port and to yield to permit the valve to beforced open by an abnormal pressure supplied thereto, a pressurecontrolled diaphragm closing one side of the casing and outwardlymovable by the pressure within the casing, and normally actuated to moveinwardly when the pressure is reduced to a predetermined point, and alever fulcrumed Within the casing at its middle portion and arranged tobe engaged at one end by said diaphragm and at its opposite with saidprojection, to move said valve stem end with said stem, to move the stemto open to open its valve on inward movement of the the valve when thediaphragm is moved indiaphragm.

wardly.

In testimony whereof, I have signed my 3. An expansion valve comprisinga casing name to this specification.

having an inlet port and an outlet port respectively adapted forconnection to the high pressure side and to the low pressure side of aclosed circuit refrigeration system, a valve stem disposed within thecasing and having a valve at one end, said stem being longitudinallymovable in one direction to close said inlet port against the pressureof the fluid supplied thereto and oppositely movable by said pressure toan open position, a spring arranged to engage said stem and to hold saidvalve in closed position against a normal pressure in said inlet portand to yield to permit the valve to be forced open by an abnormalpressure therein, a pressure controlled diaphragm arranged to close oneside of the easing and to be moved outwardly by the pressure within thecasing, means for movingsaid diaphragm inwardly when the pressure withinthe casing is reduced'to a predetermined point, an actuating stemdisposed within the casing in ali nment with said valve stem andarranged tobe moved by said diaphragm to wards said valve when thediaphragm is moved inwardly, and a lever arm arranged to be engaged atone end by said actuating stem and to engage said valve stem at itsopposite end to move the valve stem in a direction to open the valve.

4:. An expansion valve comprising a casing having an'inlet port and anoutlet port respectively adapted for connection to the high pres sureside and to the low pressure side of a closed circuit refrigerationsystem, a valve stem disposed within the casing and havin a valve at oneend, said stem being longitu inally movable in one direction to closesaid inlet port against the pressure of the fluid supplied thereto andoppositely movable by said pressure to an open position, a springarranged to engage said stem and to hold said valve in closed positionagainst a normal pressure in said inlet portand to yield to permit thevalve to be forced open by an abnormal pressure therein, a pressurecontrolled diaphragm arranged to close one side of the casing and to bemoved outwardly by the pressure within the casing, means for moving saiddiaphragm inwardly when the pressure I within the casing is reduced to apredetermined point, an actuating stem aligned'with said valve stem andtelescopically arranged at its inner end with the opposite portion ofthe valve stem from its valve with its outer end arranged forarrangement with the inner said actuating stem and at its opposite endALBERT F. SAWYER.

